They estimate the average thief will spend around two and a half minutes before the risk of discovery makes him give up.

When you're buying security, you're buying attack time which is why Sold Secure and Thatcham, the two recognised UK authorities responsible for testing car security products, both test products for double this time - and use the 5 minute deadline in their attack tests.

SOLD SECURE was an inintiative started by the police. They test product using the same methods of attack that thieves might use and will only give their approval if the product stops the car being driven away for at least five minutes.

THATCHAM is the Insurance Industry's Criteria for Vehicle Security. As well as product quality, they carry out user tests to ensure security products they approve are easy to use. All products approved by Sold Secure and Thatcham have to be submitted regularly for retest.